Study of the Surface Morphology and Optical Characteristics in InGaN/GaN MQWs Epitaxial-Layers Following Neutron Irradiation

Abstract

InGaN/GaN multiple quantum wells (MQWs) film is irradiated with neutrons (1 MeV energy, 1.2 × 1014 cm−2 total fluence). The surface morphology, film quality, and optical characteristics are characterized using atomic force microscopy (AFM), high-resolution X-ray diffraction (HRXRD), photoluminescence (PL), and Raman spectroscopy. According to the broadened (002) and (102) rocking curves of the GaN layers and InGaN satellite peaks, we infer that point defect clusters were generated near the dislocation lines and the active region of the film. These point defect clusters can lead to the enlargement and deepening of V-shaped pits in the film surface. In addition, it can be proved that the increased point defects are Ga vacancies based on the decrease of peak intensity for the active region and the enhancement of yellow band intensity from the PL spectra analysis. Moreover, strain release from Raman spectra analysis also reflects the increasing of point defects. The point defect (Ga vacancy) clusters cause the changes in both the surface morphology and the optical characteristics in the InGaN/GaN MQWs film following neutron irradiation.